Pseudomonas aeruginosa (P. aeruginosa) is a microorganism which occurs in urine, wounds, ulcers, etc. The presence of this organism in urine is a reliable indicator of an infection in the urinary tract.
Pseudomonas is a gram-negative bacterium and is commonly a saprophyte but is also an opportunistic pathogen able to establish infection and to invade when the natural resistance of an individual is severely lowered. The organism has a higher growth temperature range (41.degree. to 42.degree. C) than saprophytic pseudomonas (20.degree. to 30.degree. C) and frequently causes hospital infections associated with middle ear or urinary tract infections and wounds or ulcers that have not healed promptly. It is frequently found in patients with severe burns. The organism is naturally resistant to several antibiotics commonly used, and thus chemotherapy is very difficult.
Some outbreaks of diarrhea in adults and especially among newborn children are said to be caused by this organism.
The medium of this invention is an improved medium designed for use with the optical detection system disclosed in U.S. applications Ser. Nos. 255,533 filed May 22, 1972 now abandoned and 461,249 filed Apr. 16, 1974 now U.S. Pat. No. 3,963,355 and in the improved devices disclosed and claimed in applications filed on even date herewith by Charles, Jones, Staples, and Wiegner entitled AUTOMATED MICROBIAL ANALYZER and MACHINE AND PROCESS FOR READING CARDS CONTAINING MEDICAL SPECIMENS. These applications describe mechanism and apparatus suitable for analyzing specimens for specific microorganisms using a plastic tray or card which contains a series of dried culture media contained in separate but connectable cells, each of the media being specific to a single organism. When the sample is inserted into the card, mixed with the media in the cells, and incubated in the machine; the organism (or organisms) present in the specimen interacts with the culture medium specific to that organism and produces a change in the medium which is read by the machine to indicate the presence of that organism. The change in the medium involves a change in the light transmitting properties of the medium, i.e., a color change or change in turbidity. The change may be caused by metabolic activity of the organism, which, for example, may cause production of acid and a change in pH which causes a color change in a pH sensitive indicator in the medium. The change in the light transmitting properties of the medium also could be caused by a precipitate forming in the medium due to metabolic activity of the organism or it could be caused by growth of the organism.
The specific media designed for use in the aforesaid cards are all designed to favor growth of one microorganism and to inhibit growth of other organisms, are capable of being freeze dried, and can function in the low O.sub.2 environment of the wells of the card described in detail in said copending applications AUTOMATED MICROBIAL ANALYZER and MACHINE AND PROCESS FOR READING CARDS CONTAINING MEDICAL SPECIMENS.
We have discovered a medium which can selectively identify Pseudomonas aeruginosa organism in urine. Our medium can be used in the system developed in the aforementioned copending application entitled AUTOMATED MICROBIAL ANALYZER.
The medium is freeze dried in a well in the media card of said application AUTOMATED MICROBIAL ANALYZER and when a specimen is mixed with the medium in the well, positive results are indicated by means of a change in turbidity and pigment of the medium. The entire test can be completed within 12-18 hours, whereas current methods of detection require from 36 to 48 hours.